The amelioration of disease by Treg depletion was observed in bleomycin-induced pulmonary fibrosis (by inducing Th17 and other CD4+T cell subset responses in the lungs) (110), in irradiation-induced pulmonary fibrosis (by inhibiting the epithelial-to-mesenchymal transition in lung epithelial cells) (111), and in silica-induced lung fibrosis (112). This evidence concerns the gene CD4 and pulmonary fibrosis.